1. Field of the Invention
The invention concerns a lift device for lifting or, as the case may be, lowering a support device of a transport track segment upon which work piece carriers are provided so as to be translationally displaceable.
2. Description of the Related Art
With known flexible transport and assembly systems, a number of transport tracks or assembly tracks are connected with each other along a parallel plan, using transverse conveyors provided at right angles thereto.
According to the state of the art it is known to use so-called push-overs to push the work piece carrier from a transport track onto a transverse conveyor extending at a right angle thereto. A pusher of this type is comprised of a hydraulic or pneumatic device provided on the side of the track, of which horizontally extending rams push the work piece or, as the case may be, the carrier from the transport track onto the transverse conveyor. The problem is the displacement of the work piece or, as the case may be, the carrier, from the transverse carrier onto the transport track, that is in the reverse direction. It is a further disadvantage, that the guidance of the work piece or, as the case may be, the work piece carrier, upon the respective transport tracks or transverse carrier devices is only limitedly possible, since this would otherwise impede the pushing-over.
A further type of (reversible) translation device is known for example from DE 30 12 355 A1, comprised of transport tracks provided transverse or parallel to each other. In this device for translation of work piece carriers, work pieces, or the like, there is provided in the free space between the bands of a double belt conveyor band device a translation device with at least one translation belt extending perpendicularly to the double belt conveyor belt. This translation device has been found advantageous for employment in crossing locations of conveyor belt devices running perpendicular to each other, and makes possible a problem-free transference of the work piece carrier from one transport band to another. A problem therewith is that the transport bands or, as the case may be, transport tracks, must be positioned immediately adjacent to each other.
From DE 36 01 699 A1 a conveyor device is known, in which the transverse conveyors simultaneously assume the function of (reversible) translation, wherein a transference from the one track as well also from the other longitudinal transport track is made possible thereby. For this purpose the transverse conveyor, which crosses the longitudinal transport track, can be raised and lowered with the aid of a lifting device. These lifting devices and similar lifting systems preferably have pneumatic or hydraulic assemblies as the lifting device, which have a vertically oriented cylinder and a piston guided therein displaceable in the vertical direction for production of the lift movement, of which the piston rod is connected rigidly or via a linkage with the support device which translationally displaceably supports work piece carrier. With this type of vertically moveably guided piston or, as the case may be, piston rod, high actuation forces are necessary in order to lift the support device inclusive of the work piece carrier.